1. Field of the Invention
The present invention relates, in general, to a method and an apparatus of adjusting a focusing servo in an optical disc device and, more particularly, to adjusting a focusing servo, which can adjust the focusing position for a blank disc, on which no data recorded.
2. Description of the Related Art
In order to reproduce or record data from or on an optical disc, the adjustment of various servos, such as a focusing servo and a tracking servo, is required. The focusing position varies with the state of a disc, the mechanism and the optical pickup, and greatly influences reproduction quality and, in particular, recording quality, and thus the adjustment of the focusing position is very important.
Further, recently, a dual-layer disc having two recording layers has been commercialized to increase the storage capacity. However, the dual-layer disc is disadvantageous in that the interval between the two recording layers is not wide, and reproduction and recording quality for the recording layer that is located far away from the surface of an optical disc is relatively deteriorated. Therefore, the necessity to precisely adjust the focusing position for a typical optical disc, as well as for the dual-layer disc, is further increased.
A conventional method of adjusting a focusing position is briefly described below.
First, in the case of a disc on which recorded data exists, a focusing position is adjusted using both a reproduced Radio Frequency (RF) signal, which is obtained from the recorded data, and a tracking error signal.
However, in the case of a blank disc on which no data is recorded, an RF signal cannot be used, and thus the focusing position is adjusted using only a tracking error signal.
Meanwhile, if data is recorded on the blank disc after the focusing position has been adjusted using a tracking error signal for the blank disc, an optical disc device detects an optimal focusing position using an RF signal and a tracking error signal, and stores the optimal focusing position in memory (Electrically Erasable Programmable Read Only Memory: EEPROM) as an optimal focusing position value for the blank disc. Subsequently, when a blank disc is inserted, the focusing position is adjusted using the stored focusing position value.
However, the adjustment of focusing position using only a tracking error signal is unreliable, and thus it is difficult to detect the optimal focusing position required for data recording. Further, when the focusing position value, which is detected and stored for an arbitrary blank disc, is applied to another blank disc, because there are variations between discs, it is difficult to optimally adjust the focusing position. If a focusing position is not optimally adjusted in this way, there is a problem in that the quality of recording on a blank disc is deteriorated.